Pit approach controller vectoring 2 aircraft for same runway clears aircraft X at the lower altitude...

Attributes
ACN	427407
Time
Date	199902
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : pit
State Reference	PA
Altitude	msl bound lower : 7000 msl bound upper : 8300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Navigation In Use	Other
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Harrier
Navigation In Use	Other
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Experience	controller military : 4 controller radar : 20
ASRS Report	427407
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	other
Consequence	Other
Miss Distance	vertical : 1300
Supplementary
Air Traffic Incident	other

Narrative:

Aircraft X was handed off to me at 7000 ft. Aircraft Y was handed off at 9000 ft. The 2 aircraft were close laterally and going to land on the same runway 32. I split them up with divergent headings and then I issued a descent to 6000 ft to aircraft X. I observed the aircraft X descend out of 7000 ft and I then gave descent clearance to the aircraft Y. I assigned him 7000 ft. As the aircraft X mode C read 6500 ft, he advised me he had an RA and was climbing. I told him about the aircraft Y and quickly stopped the aircraft Y's descent. I then turned the aircraft X away from the aircraft Y. After a little scrambling and resequencing the aircraft X pilot explained the TCASII saw something below him and gave a climb RA. I didn't see any traffic anywhere they would have conflicted with him before or after. The aircraft X pilot admitted he couldn't find or see the traffic either out the window or on TCASII after all the fun was over. That aircraft Y didn't get below 8300 ft and the aircraft X never got above 7000 ft. Those 2 airplanes would have gotten too close without immediate intervention. Callback conversation with reporter revealed the following information: conversation with reporter did not add any new information on the TCASII incident. I did tell the controller reporter that it was very evident that his quick action to maintain separation may have prevented a serious conflict from occurring.

Original NASA ASRS Text

Title: PIT APCH CTLR VECTORING 2 ACFT FOR SAME RWY CLRS ACFT X AT THE LOWER ALT TO DSND. ACFT Y, 2000 FT HIGHER, IS ALSO GIVEN A DSCNT BUT IS STOPPED WHEN ACFT X RECEIVED A TCASII RA AND STARTS A CLB.

Narrative: ACFT X WAS HANDED OFF TO ME AT 7000 FT. ACFT Y WAS HANDED OFF AT 9000 FT. THE 2 ACFT WERE CLOSE LATERALLY AND GOING TO LAND ON THE SAME RWY 32. I SPLIT THEM UP WITH DIVERGENT HEADINGS AND THEN I ISSUED A DSCNT TO 6000 FT TO ACFT X. I OBSERVED THE ACFT X DSND OUT OF 7000 FT AND I THEN GAVE DSCNT CLRNC TO THE ACFT Y. I ASSIGNED HIM 7000 FT. AS THE ACFT X MODE C READ 6500 FT, HE ADVISED ME HE HAD AN RA AND WAS CLBING. I TOLD HIM ABOUT THE ACFT Y AND QUICKLY STOPPED THE ACFT Y'S DSCNT. I THEN TURNED THE ACFT X AWAY FROM THE ACFT Y. AFTER A LITTLE SCRAMBLING AND RESEQUENCING THE ACFT X PLT EXPLAINED THE TCASII SAW SOMETHING BELOW HIM AND GAVE A CLB RA. I DIDN'T SEE ANY TFC ANYWHERE THEY WOULD HAVE CONFLICTED WITH HIM BEFORE OR AFTER. THE ACFT X PLT ADMITTED HE COULDN'T FIND OR SEE THE TFC EITHER OUT THE WINDOW OR ON TCASII AFTER ALL THE FUN WAS OVER. THAT ACFT Y DIDN'T GET BELOW 8300 FT AND THE ACFT X NEVER GOT ABOVE 7000 FT. THOSE 2 AIRPLANES WOULD HAVE GOTTEN TOO CLOSE WITHOUT IMMEDIATE INTERVENTION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CONVERSATION WITH RPTR DID NOT ADD ANY NEW INFO ON THE TCASII INCIDENT. I DID TELL THE CTLR RPTR THAT IT WAS VERY EVIDENT THAT HIS QUICK ACTION TO MAINTAIN SEPARATION MAY HAVE PREVENTED A SERIOUS CONFLICT FROM OCCURRING.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Pit approach controller vectoring 2 aircraft for same runway clears aircraft X at the lower altitude to descend. Aircraft Y, 2000 ft higher, is also given a descent but is stopped when aircraft X received a TCASII RA and starts a climb.